In the mid-1970s Japanese manufacturers seemed to find the market for a sporting middleweight motorcycle a little confused. It was as if the manufacturers were not quite sure where their customers wanted them to go next. There were plenty of flash 350 and 400 bikes from the big four, but these were mostly two-strokes, with the notable exception of Honda’s fours. Going up a capacity, Yamaha was selling the overly complex TX/XS500 twin, Kawasaki and Suzuki their 500cc two-stroke twins and triples and Honda its lardy CB500 twin, which was descended from the venerable CB450 Black Bomber.

Honda was also producing a middleweight four-stroke, four-cylinder sports tourer and, in the process, it created a whole genre. It had launched its CB500/4 in 1971 to complement the class-leading CB750/4. The CB500/4 was a good 60lbs (27kg) heavier than the last British 500 in production, the Triumph Daytona, but it was a whole 10bhp more powerful. The CB500/4 was around 80lbs (36kg) lighter than the CB750/4 and the wet-sump 500cc engine was a significantly shorter lump with an over-square design that kept the cylinder height down, despite Honda deciding not to tilt the cylinder block, as on the 750.

The compact unit helped the bike to have a lower centre of gravity, as the engine was significantly lighter than that of the CB750/4, the handling of the CB500/4 and the later CB550/4 was livelier and it was a much easier bike to ride. The frame was a steel cradle with twin down-tubes and it was stiff and well-engineered for the weight and power of the bike, which contributed greatly to the bike’s handling.

Within a few years, Honda was competing with Suzuki and its softly tuned two-stroke GT550 triple. Honda boosted the capacity of its four and the CB550/4 replaced the CB500/4 in 1974, producing a popular model that remained in production until 1978.

When the first CB550s were launched in the USA, as was Honda’s practice at the time, the first models were over-bored engines mounted in the CB500 frame and cycle parts, with a capacity increased to 544cc. The new CB550/4 produced more power in the mid-range than the CB500/4, although tests indicated the two bikes had the same 105mph top speed and testers later found that the CB550/4 was actually 3mph slower than the smaller and lighter CB400F.

Like all the Honda inline fours of the period, it had two valves per cylinder and a single overhead camshaft, a chain-driven primary drive and a five-speed gearbox. On the CB550/4 there were also significant changes to the clutch operating mechanism, with the cable operating a lever on the right-hand side, rather than through a worm drive and pushrod on the left that ran through the gearbox that had caused problems for CB500/4 riders.

The SOHC engine is good, solid and uncomplicated. While the first Japanese fours were derided by die-hard British bike fans for their apparent complexities, the four is a simple design and requires little in the way of special tools to maintain and work on. Although there are lots of parts, there are simply more of them, rather than the engine being over complicated.

Honda cam-chains suffered a little from ham-fisted home maintenance and an automatic adjuster was fitted to later models with mixed results. But a four that has had its service interval 1500-mile oil changes adhered to with good quality lubricant should last well. Buyers should listen out for bottom end rumbles and knocks, as well as cam-chain rattles, though clutch noise is a feature of the model. Easily chewed up crosshead head fasteners (they look like Phillips but are actually Japanese-spec JIS – Japanese Industrial Standard and you can buy screwdrivers or bits from good tool stores) will by now have often been replaced by Allen bolts, while the original 14mm head oil filter bolt, which sits exposed to water and muck thrown up by the front wheel, may have been swapped.

Honda electric systems are good and robust too, with their wiring and components about the best to come out of Japan. Honda used a frame similar to the CB750 but stiffened up with extra bracing. The front end was excellent with their own 35mm forks but let down a little by a weak set of shock absorbers at the back, but for a 1970s Japanese motorcycle the bike handled well.

The brakes were passable, with a front disc featuring Honda’s semi-floating front caliper and there is a good-sized drum at the back. The front brake, perched on the front of the forks catching all the weather, needs regular attention to the caliper with copper grease and the steel pin that fits in the pivot needs a good clean and treating with lubrication spray regularly, while taking care not to get spray on the pads or disc.

In the UK Honda kept selling 500/4s until 1975 and didn’t include the 550/4 in its catalogue until 1976. The range began with the CB550F Super Sport, a machine popular with British buyers. This had a single colour paint job, a bigger tank, lower bars and a four-into-one (4-1) exhaust system, mirroring the popular CB400/4.

However, with a lot of early CB550 models coming into the UK today as classic imports, you might find a 550 that looks remarkably similar to the earlier 500. Charlie Garratt, from Oxford Classic Honda, explains: “If you look at a CB500K0 and a CB550K0, they look the same. The CB550K0 is not representative of the later F and K series when the frame, clocks and tanks all changed. The basic frame cradle is the same, but things like the rear footrest hangers and rear subframe are quite different. The CB550F is the sharper handling bike.”

An updated K3 series launched in the UK in 1977, which lost the trumpet-style pipes for a set of four megaphone style exhausts and was fitted with a bigger tank and lower bars. Honda launched a revamped CB550F2 at the same time as the K3 with a revised paint job and detail changes.